kern/94939: [acpi] [patch] reboot(8) fails on IBM / Intel blades
John Baldwin
jhb at freebsd.org
Thu Mar 30 19:40:25 UTC 2006
The following reply was made to PR kern/94939; it has been noted by GNATS.
From: John Baldwin <jhb at freebsd.org>
To: Nate Lawson <nate at root.org>
Cc: "Devon H. O'Dell" <dodell at ixsystems.com>, bug-followup at freebsd.org
Subject: Re: kern/94939: [acpi] [patch] reboot(8) fails on IBM / Intel blades
Date: Thu, 30 Mar 2006 14:03:57 -0500
On Thursday 30 March 2006 13:23, Nate Lawson wrote:
> John Baldwin wrote:
> > On Tuesday 28 March 2006 02:22 pm, Devon H. O'Dell wrote:
> >> On Tue, Mar 28, 2006 at 11:08:02AM -0800, Nate Lawson wrote:
> >>> The system must reset immediately following the write to this register.
> >>> OSPM assumes that the processor will not execute beyond the write
> >>> instruction. OSPM should execute spin loops on the CPUs in the system
> >>> following a write to this register.
> >> My interpretation of this is ``don't do anything else after
> >> the write to the register, because you can't expect to do
> >> it.'' Since they say that the system ``must reset immediately
> >> following the write'', it seems that this is implemented in
> >> hardware, and we can't assume that we will be able to do
> >> anything afterwards, anyway.
> >>
> >>> So I'm ok with the patch being committed if no other tasks need to
> >>> happen after this shutdown handler is called. Also, all APs should be
> >>> stopped before this happens and it should only occur once on the BSP.
> >> I was curious if anything happens after this handler is
> >> called -- if there is, we definitely need to move it back
> >> to later in the process. Again, I put the code here because it
> >> looked to me like the procedure already assumed nothing else
> >> is happening, but it sounds like there are other procedures
> >> that are in the call queue after this one.
> >
> > It really should be much later I think: in cpu_reset_real() as that
> > is the only place that you know that the APs are stopped.
>
> I'm not near a BSD box today. Is there a simple, MI way of hooking
> there that doesn't require ACPI compiled into the kernel? If it's a
> simple matter of moving it to a different shutdown handler or adding a
> way for acpi to conditionally override cpu_reset_real, that's ok with
> me. I don't want acpi being partially merged into the main kernel.
Not currently.
--
John Baldwin <jhb at FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve" = http://www.FreeBSD.org
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